~0UL is widely used to specify the maximum memory size
when calling e820_alloc_memory(), this patch to define
a MACRO for it to avoid using this magic number.
Tracked-On: #8502
Signed-off-by: Yonghua Huang <yonghua.huang@intel.com>
Reviewed-by: Junjie Mao <junjie.mao@intel.com>